Multiple genes manage how people taste sweeteners

A study published in Chemical Senses shows that genetics may play a role in how people’s taste receptors send signals, leading to a wide spectrum of taste preferences. These varied, genetically influenced responses may mean that food and drink companies will need a range of artificial sweeteners to accommodate different consumer tastes.

Based on the participants’ genetic profile, researchers were able to explain the reactions of subjects in a taste test when they sampled acesulfame K—ace K—in the laboratory. Ace K is a man-made non-nutritive sweetener commonly found in carbonated soft drinks and other products. Non-nutritive sweeteners are sweeteners with minimal or no calories. While some people find ace K sweet, others find it both bitter and sweet.

According to the researchers, two bitter taste receptor genes—TAS2R9 and TAS2R31—were able to explain some of the differences in ace K’s bitterness. These two taste receptor genes work independently, but they can combine to form a range of responses. Humans have 25 bitter-taste receptors and one sweet receptor that act like locks on gates. When molecules fit certain receptors like keys, a signal is sent to the brain, which interprets these signals as tastes.

The same researchers conducted another study—published in Chemosensory Perception—in which 122 participants tasted two stevia extracts, Rebaudioside A (Reb A) and Rebaudioside D (Reb D). While the stevia plant is becoming more popular as a natural non-nutritive sweetener, consumers have reported a variety of tastes from stevia-based sweeteners, including bitterness.

The researchers found that Reb A and Reb D bitterness varies greatly across subjects, but this was not related to whether or not participants found ace K bitter. Likewise, variation in the TAS2R9 and TAS2R31 genes did not predict Reb A and Reb D bitterness. They also found that of the stevia extracts, the participants considered Reb D to be much less bitter than Reb A.

The researchers concluded that “These data indicate that the bitterness of Reb A and Reb D cannot be predicted by ace K bitterness, reinforcing our view that bitterness is not a simple monolithic trait that is high or low in an individual. This also implies that consumers who reject ace K may not find Reb A and Reb D aversive, and vice versa. Finally, Reb D may be a superior natural non-nutritive sweetener to Reb A, as it elicits significantly less bitterness at similar levels of sweetness.”